Just constant lag/input delay

I dont get it genuinely whenever i want to play rivals/champs or even rush im just bombarded by lag and input delay when you know my opponent on the other hand is living luxury with zero lag and no input delay but yet again i have amazing wifi due to an ethernet and i never lag on any other game except this?
Now its either on the off chance that EVERY single opponent i come against is a wizard and casts curses on me or they just lag switch one or the other... OR theres another chance that the servers just dont get managed well at all